We use geodynamic modeling, in conjunction with geological and geophysical observations, to investigate the mechanics of deformation at plate boundaries, within plates, and in the underlying mantle. Our main research avenues are summarized below, and the image carousal at the bottom of this page highlights a selection of our recent projects.

Regional subduction dynamics: We use analytical and numerical modeling approaches to constrain subduction zone dynamics, with a focus on the links between sub-plate processes (e.g., mantle flow and pressure) and near-surface deformation (e.g, topography, plate velocities, and tectonics). A recent focus has been on the physical processes that dictate tectonic observables within geometrically complicated “double subduction” zones, both in general (Holt et al., 2017, GJI) and as applied to the Caribbean, Western Pacific, and India-Eurasian subduction zones (e.g., Faccenna et al., 2017, Tectonophys.; Holt et al., 2018, GJI)

Subduction zone thermal structure and metamorphism: We use numerical subduction models to investigate feedbacks between geodynamic subduction properties (e.g., slab dip, convergence rate), subduction zone thermal structure, and petrological phase transformations within dynamically evolving subduction zones (Holt and Condit, 2021, G-Cubed). As part of a recently funded NSF project, we are currently extending these generic models to specific subduction zones, and more rigorously integrating the geodynamic (slab evolution) and petrologic (phase transitions and dehydration) components of our subuction modeling approach.

Global slab and mantle dynamics: We are developing methods to investigate the strength and nature of mechanical interactions between regional plate boundaries and global-scale mantle circulation. We have developed analytical models of slab-induced mantle flow within a global upper mantle (Holt and Royden, 2021, G-Cubed) and used these to argue that Earth’s slab dip distribution is strongly affected by global flow patterns. We have also constructed global numerical subduction models to validate the results of the (more idealized) analytical models (Holt and Royden, in prep.) and, following a recent NSF award, are applying this numerical approach to investigate the imprint of global flow on Western Pacific slabs.

Plate tectonic analyses: We derive geodynamics expressions, or “rules”, to explain present-day tectonic observations (e.g., trench migration rates and directions). To do this, we focus on evaluating the validity of simple mechanical models - e.g., static force balances - to reproduce tectonic plate motions. Such rules can, in turn, be applied to evaluating the geodynamic validity of plate reconstructions, as these are often constructed without explicitly considering the dynamic feasibility of the reconstructed plate behavior.